Unhandled promise rejections still occur

Description

The problem with unhandled promise rejections do still occur (see #1012).

Minimal, Working Test code to reproduce the issue.

Reproduced the issue in a separate repo: https://github.com/joakimbeng/bull-connection-problem

The code is essentially this:

'use strict';
const Queue = require('bull');

const queue = new Queue('my-queue');

queue.on('waiting', jobId => console.log('Job waiting', jobId));
queue.on('error', error => console.error('Queue Error', error));

queue.process(job => {
  console.log('processing job', job.id);
});

queue.add({some: 'data'});

process.on('unhandledRejection', error => {
  console.error('Unhandled Rejection', error);
  process.exit(1);
});

Bull version

v3.5.2

Additional information

The two function calls that are causing this is the this.setWorkerName() and utils.isRedisReady in commands/index.js. (utils.isRedisReady is the function that's actually causing the issue in this.setWorkerName as well).

Also, the problem only occurs after the queue.process function have been called, which the #1012 did not cover.